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Gastrointestinal amebiasis is an infection of the large intestine caused by microscopic one-celled parasites commonly known as amoebas (Entamoeba histolytica). Because these parasites live in the large intestine, they travel in the feces of infected people, and can contaminate water supplies in places where sanitation is poor. The parasite can contaminate fruits and vegetables grown in areas where human feces are used as fertilizer. They can be transferred on the dirty hands of infected people who don't wash their hands often or correctly.
Once amoebas enter the mouth, they travel through the digestive system and settle in the large intestine. Harmless strains of the parasite (Entamoeba dispar) live there without causing damage. E. histolytica can live in the intestine without causing symptoms, but it also can cause severe disease. These amoebas may invade the wall of the intestine, leasing to amoebic dysentery, an illness that causes intestinal ulcers, bleeding, increased mucus production and diarrhea. These amoebas also may pass into the bloodstream and travel to the liver or, infrequently, to the brain, where they form pockets of infection (abscesses).
About 10% of the world's population is infected with amoebas, particularly people who live in Mexico, India, Central America, South America, Africa and the tropical areas of Asia. In industrialized countries, amebiasis is most common in recent immigrants and travelers who visit countries where amoebas are prevalent.
Hair loss can range from mild hair thinning to total baldness. Hair can fall out for many different reasons. Medically, hair loss falls into several categories, including:
Telogen effluvium — This common form of hair loss happens two to three months after a major body stress, such as a prolonged illness, major surgery or serious infection. It also can happen after a sudden change in hormone levels, especially in women after childbirth. Moderate amounts of hair fall out from all parts of the scalp, and may be noticed on a pillow, in the tub or on a hairbrush. While hair on some parts of the scalp may appear thinner, it is rare to see large bald spots.
Drug side effects — Hair loss can be a side effect of certain medications, including lithium, beta-blockers, warfarin, heparin, amphetamines and levodopa (Atamet, Larodopa, Sinemet). In addition, many medications used in cancer chemotherapy — such as doxorubicin (Adriamycin) — commonly cause sudden hair loss affecting the entire head.
Symptom of a medical illness — Hair loss can be one of the symptoms of a medical illness, such as systemic lupus erythematosus (lupus), syphilis, a thyroid disorder (such as hypothyroidism or hyperthyroidism), a sex-hormone imbalance or a serious nutritional problem, especially a deficiency of protein, iron, zinc or biotin. These deficiencies are most common in people on restrictive diets and women who have very heavy menstrual flow.
Tinea capitis (fungal infection of the scalp) — This form of patchy hair loss happens when certain types of fungi infect the scalp. This causes the hair to break off at the scalp surface and the scalp to flake or become scaly. Tinea capitis is a common form of patchy hair loss in children.
Alopecia areata — This is an autoimmune disease that causes hair to fall out in one or more small patches. The cause of this condition is unknown, although it is more common in people who have other autoimmune diseases. When the same process causes total loss of hair from the scalp it is known as alopecia totalis.
Traumatic alopecia — This form of hair loss is caused by hairdressing techniques that pull the hair (tight braiding or cornrowing), expose hair to extreme heat and twisting (curling iron or hot rollers) or damage the hair with strong chemicals (bleaching, hair coloring, permanent waves). In addition, some people have an uncommon psychiatric disorder (trichotillomania) in which compulsive hair pulling and twisting can cause bald spots.
Hereditary pattern baldness, or androgenetic alopecia — In men, hair loss may follow the typical male pattern (receding front hairline and/or thinning hair at the top of the head). This is the most common type of hair loss, and it can begin at any time in a man's life, even during his teen years. It usually is caused by the interaction of three factors: an inherited tendency toward baldness, male hormones and increasing age. Many women will develop some degree of female-pattern baldness. In women, thinning occurs over the entire top or crown of the scalp, sparing the front of the scalp.
Multiple sclerosis (MS) is a disabling neurological illness. It affects the brain and spinal cord. The disease is usually progressive. This means it worsens over time.
An insulating sheath called myelin normally surrounds nerve cells. Myelin helps to transmit nerve impulses.
In MS, the myelin sheath becomes inflamed or damaged. This disrupts or slows nerve impulses. The inflammation leaves areas of scarring called sclerosis.
Multiple sclerosis may also damage nerve cells, not just their myelin lining.
The disruption of nerve signals causes a variety of symptoms. MS can affect a person's vision, ability to move parts of the body, and ability to feel sensations (such as pain and touch).
Symptoms usually come and go. Periods when symptoms suddenly get worse are called relapses. They alternate with periods when symptoms improve, called remissions.
Many people have a long history of MS attacks over several decades. In these cases, the disease may worsen in "steps," when the attacks occur. For others, the disease worsens steadily. In a minority of patients, MS causes relatively few problems.
Scientists believe MS is an autoimmune disease. This means the immune system mistakenly attacks its own body. In this case, the body attacks the myelin sheaths of the nerves.
Several viruses have been linked to MS. But they are not proven causes of the disease. Fever, other physical or emotional stress may contribute to a flare-up of symptoms. The timing, duration and damage of MS attacks are unpredictable.
The symptoms of MS usually begin before age 40. But people between ages 40 and 60 sometimes are affected. Having a close relative with MS increases your chances of developing the disease.
Myocarditis is an inflammation of the heart muscle that decreases the ability of the heart to pump blood normally. It can be caused by:
An infection —Many infections have been associated with myocarditis. Some of the more likely germs include:
Viral infections — A common cause of myocarditis. Many different viruses can cause myocarditis. Examples include adenovirus, coxsackievirus, Epstein-Barr virus, HIV, varicella (chickenpox) and human herpes virus 6. Often the person has no preceding symptoms of a cold, cough, nasal congestion or rash and only becomes aware of the infection when heart failure occurs.
Bacteria — Rarely, myocarditis is a complication of endocarditis, an infection of the heart valves and the lining inside the heart's chambers caused by bacteria. In some people with diphtheria, a toxin (poison) produced by C. diphtheriae bacteria causes a form of myocarditis that leads to a flabby, stretched-out heart muscle. Because the flabby, enlarged heart cannot pump blood efficiently, severe heart failure may develop within the first week of illness.
Chagas' disease — This infection, caused by the protozoan Trypanosoma cruzi, is transmitted by an insect bite. In the United States, myocarditis caused by Chagas' disease is most common among travelers to or immigrants from Central and South America. In up to one-third of people with Chagas' disease, a form of chronic (long-term) myocarditis develops many years after the first infection. This chronic myocarditis leads to significant destruction of heart muscle with progressive heart failure.
Lyme myocarditis — Lyme disease, an infection caused by the tick-borne bacterium Borrelia burgdorferi, can cause myocarditis or other heart problems.
Toenail fungus is a condition that disfigures and sometimes destroys the nail. It is also called onychomycosis
Toenail fungus can be caused by several different types of fungi. Fungi are microscopic organisms related to mold and mildew.
These fungi thrive in the dark, moist and stuffy environment inside shoes. As they grow, fungi feed on keratin. Keratin is the protein that makes up the hard surface of the toenails.
Factors that increase the risk of developing toenail fungus include:
Wearing tight-fitting shoes or tight hosiery
Practicing poor foot hygiene
Wearing layers of toenail polish, which doesn't allow the nail to breathe
Being a military personnel, athlete or miner. This is because toenail fungi may spread from foot to foot on the floors of showers and locker rooms.
Having a chronic illnesses, such as diabetes or HIV
Having a circulatory problem that decreases blood flow to the toes
However, many people with toenail fungus have no clear risk factors.
Toenails on the big toe and little toe are the most likely to develop a toenail fungus. This may be partly because the big toe and little toe are constantly exposed to friction from the sides of shoes.
Shingles, also known as herpes zoster or just zoster, occurs when a virus in nerve cells becomes active again later in life and causes a skin rash.
The virus that causes shingles, the varicella-zoster virus, is the same virus that causes chickenpox. It is a member of the herpes virus family. Once you have had chickenpox, varicella-zoster virus remains in your body's nerve tissues and never really goes away. It is inactive, but it can be reactivated later in life. This causes shingles.
Doctors aren't sure how or why the varicella-zoster virus reactivates, but they believe your immune system's response to the virus weakens over the years after childhood chickenpox. When the virus reactivates, it travels through nerves, often causing a burning or tingling sensation in the affected areas. Two or three days later, when the virus reaches the skin, blisters appear grouped along the affected nerve. The skin may be very sensitive, and you may feel a lot of pain.
If you have had chickenpox, you are at risk of developing shingles. However, the virus doesn't reactivate in everyone who has had chickenpox. Shingles most often appears in people older than 50 and in people with weakened immune systems. If you are having treatment for cancer, for example, you are more likely to get shingles. People with HIV commonly get shingles, which is often one of the first signs that the immune system is in trouble.
Your chances of getting shingles increase as you get older, although the disease can occur at any age. When shingles appears in children, which is uncommon, it usually is very mild. Up to 20% of people in the United States develop the disease at some point.
Potential complications of shingles include:
Post-herpetic neuralgia — About 10% of adults who get shingles experience long-term pain in the area of skin where blisters occurred, even after the rash has healed completely. This condition may last for months or, very rarely, years. Severe pain is most common in older patients and often is accompanied by extreme sensitivity to heat and cold in the affected area of skin.
Herpes zoster ophthalmicus — This occurs when shingles involves the eye. Herpes zoster ophthalmicus can affect your vision, even causing blindness, and can be very painful.
Otic zoster — Also called Ramsay Hunt syndrome or geniculate zoster, otic zoster occurs when shingles affects the ears. It can cause hearing loss.
Bell's palsy — Shingles can cause Bell's palsy, in which a facial nerve is paralyzed.
The esophagus is the muscular tube that carries food through the chest, from the mouth to the stomach. Normally you don't feel it except when you are swallowing. However, if the inside lining of your esophagus becomes inflamed, you may experience pain or problems with swallowing. This inflammation of the esophagus is called esophagitis.
The peritonsillar space lies between each tonsil and the wall of the throat. An infection can cause a pus-filled swelling (abscess) to develop in this space. Peritonsillar abscesses, also called quinsy, usually occur as a complication of tonsillitis. They most often are caused by "strep throat" bacteria (group A beta-hemolytic streptococci).
If a peritonsillar abscess is not treated promptly, the infection can spread to the neck, roof of the mouth and lungs. The swelling can push the tonsil closest to it into the center of your throat and move the uvula (the flap of tissue hanging in the back of your throat) from the center toward the unaffected side of your throat. In severe cases, the swelling can make breathing difficult or can close your airway.
Peritonsillar abscesses most often are found in older children, adolescents and young adults. They are less common than in the past because tonsillitis now often is treated with antibiotics, which destroy the infection-causing bacteria.
Scabies is a mite infestation of the skin. The scabies mite, also known as the human itch or mange mite, causes intense itching, and it is contagious. When a person catches scabies, pregnant female mites dig burrows in the skin and lay eggs along the way. After three to eight days, the eggs hatch and the young mites travel up the burrows to the skin surface. There they grow to adulthood and mate, after which the females become pregnant and continue the skin infestation. Once a female mite finishes laying her eggs, she spends the rest of her 2-month life span at the deep end of her tunnel. Mite tunnels may be visible in the skin of a person who has scabies, although intense scratching often distorts their appearance.
Tremor is the shaky movements of your hands, limbs, head or voice that you can't control. Sometimes tremor is a normal reaction to a situation such as fear, fatigue or anger. It also can be a side effect of too much caffeine, a medication, or withdrawal from a drug or medicine. When tremor occurs during activities and there is no emotional or chemical cause, it can be a sign of a neurological disease called essential tremor.
Essential tremor is different than Parkinson's disease, another neurological illness. Essential tremor is most noticeable when your body is in action, such as when you are writing, typing or pouring a beverage. In contrast, the tremors of Parkinson's are more noticeable at rest.